The present invention relates to a novel method of electrolysis of an alkali metal chloride solution using a cation exchange membrane. More particularly, the present invention relates to an ion exchange membrane electrolysis method carrying out electrolysis by bringing an anode, a cation exchange membrane and a cathode into contact with each other, thereby utilizing the insulating property inherent in the cation exchange membrane.
It has heretofore been known and conventional that ion exchange membrane electrolysis is effected not by bringing the anode, the cation exchange membrane and the cathode into contact with each other, but by maintaining uniform electrode-cation exchange membrane spacing. Since the spacing inevitably results in enhanced cell voltage, a series of studies have been focussed on how to minimize the electrode-cation exchange membrane spacing in an electrolysis method using ion exchange membranes.
It is an object of the present invention to provide an electrolysis method of an alkali metal chloride solution which is capable of reducing cell voltage remarkably.
Another object of the present invention is to provide an electrolysis method of an alkali metal chloride solution capable of obtaining the product in a high quality, namely, alkali metal hydroxide liquor containing alkali metal chloride in a low concentration.
Still another object of the present invention is to provide a method capable of converting asbestos or modified asbestos diaphragm cells to ion exchange membrane cells, whereby alkali metal hydroxide containing alkali metal chloride in a low concentration is produced.
A further object of the present invention is to provide an electrolysis method free from environmental pollution and danger to human bodies by remodeling asbestos or modified asbestos diaphragm cells to ion exchange membrane cells.
A still further object of the present invention is to provide a method of carrying out electrolysis with anode-cathode spacing reduced to substantially the same distance as the membrane thickness, whereby electrolysis is conducted with a low cell voltage and a high cell liquor concentration to result in reduction in the operating cost.
In order to eliminate the defect relating to the cell voltage in a conventional method of an ion exchange membrane electrolysis, it has been determined by the present inventors through a series of studies that the foregoing objects can be attained by bringing the electrodes into contact with the ion exchange membrane. Up to now, it has been thought, even by experienced workers, that adhesion of the electrodes to the ion exchange membrane would cause damage to and loss of the ion exchange membrane or lower the performance of the ion exchange membrane. The present inventors have directed their attention to the insulating property inherent in an ion exchange membrane and then attempted to utilize the insulating property wherein the electrodes are fastened to the ion exchange membrane and electrolysis is performed. Through this test, it has been determined by the present inventors that neither damage nor a decrease in performance takes place, which has never been expected.